Rachet type prosthetic lock

ABSTRACT

A prosthetic lock assembly of the ratchet type for connecting a liner for a prosthetic socket to a prosthesis. The lock assembly includes a two part locking mechanism held together by suitable fasteners. Removal or loosening of the fasteners enables a user to separate the two parts from one another in the event a sock gets into and jams the locking mechanism. In a first set of four embodiments, a latch is formed in a first part of the locking mechanism and in a second set of four embodiments, the latch is formed in a second part of the locking mechanism. The lock assembly may be mounted internally or externally of the prosthetic socket. The first part of the locking mechanism may be a laminating ring or a thermoforming plate and the second part may be a mounting block with or without a pyramid for controlling a prosthetic pylon.

RELATED APPLICATIONS

[0001] This disclosure is a division of a co-pending disclosure of thesame title by the same inventor, filed Jul. 18, 2000, bearing Ser. No.09/618,511.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates, generally, to prosthetic locking devices.More particularly, it relates to a prosthetic lock of the ratchet type.

[0004] 2. Description of the Prior Art

[0005] A prosthetic locking device is positioned at the distal end of aprosthetic socket. Its function is to enable releasable locking of asocket liner of the type worn on a residual limb to a prosthetic devicesuch as an artificial leg and foot assembly. More particularly, anaperture is formed in a prosthetic socket at a distal end thereof forreceiving a serrated, elongate locking pin therethrough. The elongatelocking pin is engaged to the distal end of a socket liner. A lockingmeans is positioned between the distal end of the socket and theproximal end of the prosthetic device. The locking means releasablyengages the elongate locking pin, thereby interconnecting the socketliner and the prosthetic device.

[0006] There are two different types of prosthetic locking devices incurrent use. The first type is known as the ratchet type and the secondis known as the clutch type. In a ratchet type lock, a serrated,elongate locking pin is selectively engaged by a pawl. In a clutch type,a serrated, elongate locking pin is engaged by the teeth of a movablymounted gear that can rotate only in one direction.

[0007] The primary drawback of a ratchet type lock derives from thedistance between serrations; a socket slack is created whereby theresidual limb moves up and down as the patient walks. Another drawbackarises when a patient accidentally jams a prosthetic sock into the holeof the lock. The sock disables the ratchet and pawl locking mechanismand the socket can be removed only by cutting it off, thereby destroyingit. This type of jamming is a very common occurrence.

[0008] The primary drawback of a clutch type prosthetic lock is that ithas a greater height extent than a ratchet type lock, to accommodate theheight of the one-way gear. Moreover, its operation is silent. Mostamputees dislike this feature of clutch type locks because they preferthe reassuring clicking sound made by a ratchet type lock when it ispositively engaged.

[0009] What is needed, then, is a ratchet type lock that provides areassuring audible feedback when it is positively seated, but which hasa low profile. Moreover, the new ratchet lock should enable removal of aresidual limb from a socket, even if a prosthetic sock has become lodgedin the locking means.

[0010] However, in view of the prior art in at the time the presentinvention was made, it was not obvious to those of ordinary skill in thepertinent art how the identified needs could be fulfilled.

SUMMARY OF INVENTION

[0011] The longstanding but heretofore unfulfilled need for an improvedratchet type locking assembly is now met by a new, useful, andnonobvious invention. The novel locking assembly interconnects aprosthetic socket liner to a pylon that forms a part of a prostheticleg. An elongate locking pin depends from a distal end of the socketliner and extends into releasable locking engagement with the novel lockassembly through an opening formed in the distal end of the prostheticsocket.

[0012] In all embodiments, the novel lock assembly includes two majorparts that abut one another and which are held in such abuttingrelationship by suitable fasteners. Removal or at least loosening of thefasteners enables total or at least partial separation of said two majorparts, respectively. When fully or partially separated, any jammingproblems that may occur may be overcome in the absence of any need tocut the prosthetic socket.

[0013] The first major part may take the form of a laminating ring or athermoforming plate. The former is used where the prosthetic socket is acarbon or fiberglass laminate and the latter is used where theprosthetic socket is a thermoformed plastic.

[0014] The second major part may take the form of a lock body with anintegral pyramid for controlling the pylon or a lock body without apyramid. Embodiments with integral pyramids save space and cost bycombining the lock, mounting plate, and the pyramid or prior art deignsinto a single piece. The embodiments with pyramids are subjected to sideloads at heel strike.

[0015] The second major part may also take the form of a mounting platewith a pyramid or without a pyramid. The novel latch means that engagesthe elongate locking pin may be positioned within the first major partor the second major part of the lock assembly. Moreover, the lockassembly may be mounted within a prosthetic socket or externallythereof.

[0016] In a first embodiment, the novel prosthetic lock assembly forinterconnecting a liner for a prosthetic socket with a pylon that formsa part of a leg prosthesis includes a first major part in the form of alaminating ring having a central bore formed therein. The central borehas a longitudinal axis substantially coincident to a longitudinal axisof the prosthetic socket liner. An elongate latching pin depends fromthe liner and is adapted to be slidingly received within the centralbore. The elongate latching pin has a plurality of closely spaced apart,annular ratchet means formed therein along the length thereof. Theannular ratchet means are disposed normal to a longitudinal axis of theelongate latching pin. As mentioned above, an opening is formed in thedistal end of the prosthetic socket and the elongate latching pinextends through that opening to engage the novel lock assembly.

[0017] In the first embodiment, for use with laminated prostheticsockets, the novel lock assembly includes a lock body having an integralpyramid. The lock body abuttingly engages a laminating ring and fastenermeans are provided for releasably interconnecting the laminating ringand the lock body. A latching means is formed in the lock body forreleasably engaging an elongate latching pin. In this way, the socketliner is connected to the prosthetic device when the elongate latchingpin is engaged by the latching means. Loosening or removal of thefastener means enables separation of the laminating ring and the lockbody so that jamming of the latching means by a sock may be overcome inthe absence of a need to cut off the socket.

[0018] A latching block that forms a part of the novel latching means ispositioned in an opening formed in the lock body. The latching block isadapted to engage the elongate latching pin between contiguous ratchetsof the annular ratchet means and to hold the elongate latching pinagainst longitudinal movement when so engaged. The opening has an extentin a preselected dimension greater than an extent of the latching blockin a corresponding dimension so that the latching block has a firstposition at a first end of the opening, a second position at a secondend of the opening, and an infinite plurality of positions therebetween.

[0019] A bias means is positioned within the opening and urges thelatching block into engaging relation to the elongate latching pin whenthe bias means is in repose. A release means for overcoming the biasmeans is provided so that the elongate latching pin is removable fromthe lock body and hence from the laminating ring when the release meansis activated.

[0020] The release means further includes a bore formed in an annularperipheral edge of the lock body. The bore is disposed radially withrespect to the longitudinal axis of the prosthetic liner. A push buttonmeans extends through the bore and a first end of the push button meansabuttingly engages the latching block and a second end of the pushbutton means projects radially outwardly from the bore so that a usercan press the second end of the push button means and displace thelatching block, overcoming the bias of the bias means, therebydisengaging the latching block from the elongate latching pin so thatthe liner may be removed from the prosthetic socket.

[0021] In a second embodiment, the lock ring has no pyramid. In a thirdembodiment, used in conjunction with a plastic socket, a thermoformingplate replaces the laminating ring but the locking plate still has apyramid. In a fourth embodiment, the thermoforming plate replaces thelaminating ring and the locking plate has no pyramid.

[0022] All of the first four embodiments are mounted externally relativeto the prosthetic socket. Four additional embodiments are disclosed,each of which is positioned within the prosthetic socket. In the finalfour embodiments, the latching block is positioned in an opening formedin the laminating ring or the thermoforming plate. Accordingly, thelaminating ring in such embodiments is referred to as the laminatinglock body and the thermoforming plate is referred to as thethermoforming lock body. The part corresponding to the lock body of thefirst four embodiments is referred to as a mounting plate with pyramidor a mounting plate without pyramid because it performs no lockingfunction in said embodiments. However, it is releasably engaged to thelaminating lock body or the thermoforming lock body with fasteners as inthe first four embodiments. Thus, the anti-jamming feature is providedin all eight embodiments.

[0023] A primary object of this invention is to provide a ratchet typeprosthetic locking device that does not require cutting of a socket whenthe locking device is jammed.

[0024] Another important object is to provide a ratchet type lockingdevice so that users thereof are assured by audible clicking sounds thatthe device is working.

[0025] Another object is to provide such a device of the type that canbe mounted inside or outside of a prosthetic socket and which may beprovided with or without an integral pyramid for controlling a pylon.

[0026] Another important object is to provide a ratchet type lockingdevice having a reduced longitudinal extent relative to ratchet typelocking devices of the prior art.

[0027] These and other important objects, advantages, and features ofthe invention will become clear as this description proceeds.

[0028] The invention accordingly comprises the features of construction,combination of elements, and arrangement of parts that will beexemplified in the description set forth hereinafter and the scope ofthe invention will be indicated in the claims.

BRIEF DESCRIPTION OF DRAWINGS

[0029] For a fuller understanding of the nature and objects of theinvention, reference should be made to the following detaileddescription, taken in connection with the accompanying drawings, inwhich:

[0030]FIG. 1 is an exploded view of a first embodiment of the invention;

[0031]FIG. 1A is a first perspective view of said first embodiment inits assembled configuration;

[0032]FIG. 1B is a second perspective view of said first embodiment inits assembled configuration;

[0033]FIG. 1C is a top plan view of the latching block;

[0034]FIG. 1D is a sectional view taken along line 1D-1D on FIG. 1C;

[0035]FIG. 2 is an exploded view of a second embodiment of theinvention;

[0036]FIG. 2A is a first perspective view of said second embodiment inits assembled configuration;

[0037]FIG. 2B is a second perspective view of said second embodiment inits assembled configuration;

[0038]FIG. 3 is an exploded view of a third embodiment of the invention;

[0039]FIG. 3A is a first perspective view of said third embodiment inits assembled configuration;

[0040]FIG. 3B is a second perspective view of said third embodiment inits assembled configuration;

[0041]FIG. 4 is an exploded view of a fourth embodiment of theinvention;

[0042]FIG. 4A is a first perspective view of said fourth embodiment inits assembled configuration;

[0043]FIG. 4B is a second perspective view of said fourth embodiment inits assembled configuration;

[0044]FIG. 5 is an exploded view of a fifth embodiment of the invention;

[0045]FIG. 5A is a first perspective view of said fifth embodiment inits assembled configuration;

[0046]FIG. 5B is a second perspective view of said fifth embodiment inits assembled configuration;

[0047]FIG. 6 is an exploded view of a sixth embodiment of the invention;

[0048]FIG. 6A is a first perspective view of said sixth embodiment inits assembled configuration;

[0049]FIG. 6B is a second perspective view of said sixth embodiment inits assembled configuration;

[0050]FIG. 7 is an exploded view of a seventh embodiment of theinvention;

[0051]FIG. 7A is a first perspective view of said seventh embodiment inits assembled configuration;

[0052]FIG. 7B is a second perspective view of said seventh embodiment inits assembled configuration;

[0053]FIG. 8 is an exploded view of an eighth embodiment of theinvention;

[0054]FIG. 8A is a first perspective view of said eighth embodiment inits assembled configuration; and

[0055]FIG. 8B is a second perspective view of said eighth embodiment inits assembled configuration.

DETAILED DESCRIPTION

[0056] Referring now to FIG. 1, it will there be seen that the referencenumber 10 denotes a first illustrative embodiment of the presentinvention.

[0057] In this first embodiment, the latching mechanism is external tothe socket and is preferably formed of stainless steel. Reducer 12surmounts and screw threadedly engages latching pin 14. Latching pin 14is attached by suitable means, not shown, to the distal end of a socketliner, not shown, and extends through an aperture formed in the distalend of a prosthetic socket, not shown. A plurality of closely,equidistantly spaced, annular serrations 15 are formed in latching pin14.

[0058] Laminating ring 16 is centrally apertured as at 18 to receivelatching pin 14 therethrough. Laminating ring 16 is placed onto thedistal end of a positive cast of the patient's residual limb and securedinto position with the components of a fabrication kit, not shown. Alaminating fabric is draped onto the cast and tied around the laminatingring. A laminating resin is then applied and allowed to cure.

[0059] Lock body 20 is formed independently of laminating ring 16 and isdisposed in abutting, underlying relation thereto when novel prostheticlocking means 10 is assembled, as perhaps best understood in connectionwith FIGS. 1A and 1B. An opening 22 is formed in lock body 20 andextends therethrough. The size and shape of opening 22 is sufficient toaccommodate therein a latching block 24 and a latching spring 26. Anopening 28 extends through latching block 24 and a sharp ridge 30extends from a peripheral edge of said opening as best understood inconnection with FIGS. 1C and 1D. Blind bore 32 is formed in a rear wallof latching block 24 to accommodate a first end of latching spring 26.Opening 22 of lock-body 20 includes a narrow extended part 22 a thataccommodates the second end of said latching spring when the novellocking mechanism is assembled. Therefore, when latching spring 26 is inrepose, it urges latching block 24 and hence sharp ridge 30 intoabutting engagement with latching pin 14 such that said sharp ridge 30is disposed between two of said serrations 15. Sharp ridge 30 fullyoccupies the space between the serrations and there is therefore noslack to cause pistoning when the patient walks.

[0060] When it is desired to disengage sharp ridge 30 from locking pin14, push button handle 34 is manually depressed. A first end of pushbutton rod 36 is in screw threaded engagement with an internallythreaded bore formed in said push button handle 34. A second end of pushbutton rod 36 is in screw threaded engagement with an internallythreaded bore 24 a formed in latching block 24. Push button rod 36extends through unthreaded bore 38 formed in the peripheral edge of lockbody 20. In this way, depression of push button handle 34 displaceslatching block 24, compressing latching spring 26, so that sharp edge 30disengages from serrations 15 and enables withdrawal of locking pin 14from aperture 18 formed in laminating ring 16.

[0061] When push button handle 34 is released, locking spring 26 unloadsand returns latching block 24 to its position of repose within lock body20. This positions sharp edge 30 in the path of travel of serrations 15when latching pin 14 is reintroduced through aperture 18. Suchreintroduction causes latching spring 26 to quickly load and unload,i.e., to become compressed and expanded, as said serrations pass by. Thesharp edge 30 thus enters into each space between the serrations andwithdraws therefrom as they travel by. Each entrance, under the biasprovided by latching spring 26, produces the characteristic clickingsound of a ratchet type prosthetic lock. This sound reassures the wearerthat the locking mechanism is working. When the last click is heard, thewearer knows that latching pin 14 is fully inserted into lock body 20.

[0062] This novel latching means reduces the profile of the novellocking means, relative to prior art locking means, because it occupiesthe same plane as the lock body.

[0063] Although a good socket liner provides a sufficient cushionbetween a residual limb and a prosthetic socket, some patients prefer toposition a sock over the liner for further comfort. An opening is formedin the distal end of the sock to accommodate latching pin 14.Accordingly, the sock can enter into opening 18 formed in laminatingring 16 and jam the locking mechanism. The formation of laminating ring16 and lock body 20 as two separate parts solves this problem. Aplurality of openings, collectively denoted 40 in FIG. 1, are formed inlock body 20. Each opening 40 has a longitudinal axis parallel to thelongitudinal axis of latching pin 14. A matching plurality of internallythreaded openings are formed in bottom wall 117 of laminating ring 16,and screws 42 (FIG. 1A) interconnect said lock body 20 and saidlaminating ring 16. In the event of a jam, whether caused by a sock orother foreign matter, said screws 42 are loosened or removed, allowinglock body 20 to disconnect from laminating ring 16. This allows the biasprovided by the sock to overcome the bias of latching spring 26 and thesock can be removed from opening 18 in the absence of any need to cutthe prosthetic socket.

[0064] Pyramid 44 depends from lock body 20 and provides orientation fora pylon of a prosthetic leg, not shown.

[0065] Lock body 20 replaces the conventional lock, mounting plate, andconventional pyramid of the prior art and enables the provision of aratchet type locking means having a much lower profile, or longitudinalextent, than the ratchet type locking means of the prior art, bycombining said parts into a single low profile part.

[0066] The second embodiment of the invention is depicted in FIGS. 2,2A, and 2B. It differs from the first embodiment in that it has a flatlock body 20 a with no integral pyramid, but all other parts are thesame as indicated by the same reference numerals. Accordingly, aconventional pyramid is attached to said lock body 20 a. Lock body 20 arepresents an improvement over the prior art because it combines theconventional lock and the conventional mounting plate into a single parthaving a smaller profile or longitudinal extent than the combinedprofiles of the prior art lock and mounting plate.

[0067] The third embodiment of the invention is depicted in FIGS. 3, 3A,and 3B. The assembly is externally mounted, is preferably formed oftitanium, and includes a pyramid for pylon control. All of the parts arethe same as in the first embodiment, with the exception that laminatingring 16 is replaced by thermoforming plate 16 a that is placed onto thedistal end of the positive cast of the residual limb and secured inplace with the components of the fabrication kit. The thermoplastic forthe socket is heated in an oven and then drape formed or vacuum formedonto the cast and the support plate.

[0068]FIGS. 4, 4A, and 4B depict the fourth embodiment. It includesthermoforming plate 16 a of the third embodiment and the flat lock body20 a of the second embodiment. The assembly is externally mounted, ispreferably formed of titanium, and has no integral pyramid.

[0069] The lock assembly of the fifth embodiment, depicted in FIGS. 5,5A, and 5B, is internally mounted and preferably formed of stainlesssteel. Latching block 24 and latching spring 26, in this embodiment, arepositioned in a cavity formed in laminating lock body 16 b, which hastapered sidewalls, and not in lock body 20 or 20 a as in theexternally-mounted embodiments just described. Accordingly, aninternally threaded opening 38 a is formed in a peripheral edge of saidlaminating lock body 16 b and not in said lock body 20 or 20 a. Due tothe internal mounting, it is necessary to provide a means for preventinglaminating resin from fouling the latching mechanism. The means includesa pushbutton dummy, not shown, that is screwed into a laminating lockdummy, not shown. Fasteners are employed to fasten the laminating lockdummy to mounting plate 20 b and said laminating lock body 16 b islaminated into the socket. A cut out is then formed in the socket toexpose the pushbutton dummy which is then unscrewed and removed from thelaminating lock dummy. The fasteners are then removed so that thelaminating lock dummy and mounting plate are disconnected. Thelaminating lock dummy is then replaced with real laminating lock body 16b and the real pushbutton rod 36 is screwed into said real laminatinglock body 16 b.

[0070] Note that mounting plate 20 b is circumscribed by a laminatingring.

[0071] This fifth embodiment shares the same advantages as that of thefirst embodiment, and includes further advantages as well. Specifically,lateral stresses resulting from heel strikes or other activities are nottransferred from mounting plate 20 b to the socket by means offasteners. Instead, the stresses are transferred from mounting plate 20b to the socket directly through laminating lock body 16 b. Thisincreases the weight rating of the lock whereas the strength rating ofthe fasteners would reduce said weight rating. Moreover, the fastenersbetween mounting plate 20 b and laminating lock body 16 b are notsubjected to lateral stress but only to the weight of the prosthesis.Such weight represents only a nominal force.

[0072] The sixth embodiment, depicted in FIGS. 6, 6A, and 6B, is alsointernally mounted and dummy parts are used to avoid fouling the latchmechanism. It shares the same structure and advantages as the fifthembodiment in all respects except that it includes mounting plate 20 cwhich has no integral pyramid.

[0073]FIGS. 7, 7A, and 7B depict the seventh embodiment. It is similarto the third and fourth embodiments in that it includes thermoforminglock body 16 c and is different from said third and fourth embodimentsin that the latching means is positioned within said thermoforming lockbody 16 c. It includes mounting plate 20 b having pyramid 44.

[0074] The final embodiment is depicted in FIGS. 8, 8A, and 8B. Itincludes thermoforming lock body 16 c of the seventh embodiment andmounting plate 20 c with no pyramid of the sixth embodiment.

[0075] All of the embodiments provide the desired clicking noise whenthe elongate locking pin is being inserted into the locking means, andall of the embodiments have a lower profile than the ratchet type andclutch type locking devices heretofore known. Moreover, the inventivestructure is the first, anywhere in the world, to enable jams of thelocking mechanism to be overcome in the absence of any need to cut aprosthetic socket. The inventive structure is also highly versatile,being usable with laminated or plastic sockets, and being mountableexternally or internally of a socket.

[0076] It will be seen that the objects set forth above, and those madeapparent from the foregoing description, are efficiently attained. Sincecertain changes may be made in the above construction without departingfrom the scope of the invention, it is intended that all matterscontained in the foregoing description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

[0077] It is also to be understood that the following claims areintended to cover all of the generic and specific features of theinvention herein described, and all statements of the scope of theinvention which, as a matter of language, might be said to falltherebetween.

[0078] Now that the invention has been described,

1. A prosthetic lock assembly for interconnecting a liner for aprosthetic socket with a prosthesis, comprising: a laminating lock bodyhaving a central bore formed therein, said central bore having alongitudinal axis substantially coincident to a longitudinal axis ofsaid prosthetic socket liner; an elongate latching pin adapted to beslidingly received within said central bore, said elongate latching pinhaving a plurality of closely spaced apart, annular ratchet means formedtherein along the length thereof, said annular ratchet means beingdisposed normal to a longitudinal axis of said elongate latching pin;said elongate latching pin adapted to depend from a distal end of saidprosthetic socket liner; a mounting plate adapted to abuttingly engagesaid laminating lock body; fastener means for releasably interconnectingsaid laminating lock body and said mounting plate; latching means formedin said laminating lock body for releasably engaging said elongatelatching pin; an opening formed in said laminating lock body; acentrally apertured latching block disposed within said opening; saidlatching block adapted to engage said elongate latching pin betweencontiguous ratchets of said annular ratchet means and to hold saidelongate latching pin against longitudinal movement when so engaged;said opening having an extent in a preselected dimension greater than anextent of said latching block in a corresponding dimension so that saidlatching block has a first position at a first end of said opening, asecond position at a second end of said opening, and an infiniteplurality of positions therebetween; a bias means positioned within saidopening, said bias means urging said latching block into engagingrelation to said elongate latching pin when said bias means is inrepose; and release means for overcoming said bias means so that saidelongate latching pin and hence said socket liner are removable fromsaid laminating lock body and from said mounting plate when said releasemeans is activated; whereby said liner is connected to said prosthesiswhen said elongate latching pin is engaged by said latching means; andwhereby loosening or removal of said fastener means enables separationof said laminating lock body and said mounting plate so that jamming ofsaid latching means by a sock may be overcome in the absence of a needto cut off said socket.
 2. The prosthetic lock assembly of claim 1,wherein said release means further comprises: a bore formed in anannular peripheral edge of said laminating lock body, said bore beingdisposed radially with respect to said longitudinal axis of saidprosthetic liner; a push button means that extends through said bore, afirst end of said push button means abuttingly engaging said latchingblock and a second end of said push button means projecting radiallyoutwardly from said bore; whereby a user presses said second end of saidpush button means and displaces said latching block, overcoming the biasof said bias means, thereby disengaging said latching block from saidelongate latching pin so that said liner may be removed from saidprosthetic socket.
 3. The prosthetic lock assembly of claim 1, whereinsaid laminating lock body and said mounting plate are positionedexternally to said socket.
 4. The prosthetic lock assembly of claim 1,wherein said laminating lock body and said mounting plate are positionedwithin said socket.